The critically endangered White-bellied Heron (Ardea insignis) is a piscivorous visual forager that prefers to forage in fast-flowing freshwater rivers. This study highlights White-bellied Heron foraging behavior in the fast-flowing rivers of Namdapha Tiger Reserve during 2013–2017. The herons spent significantly more time and also made more foraging attempts while foraging in shallow water (foraging time: 61.45 ± 15.55%; strike rate: 1.70 strikes/hr). Herons were more successful in catching fishes when they foraged facing upstream (capture rate: 0.62 fishes caught/hr) with increased capture efficiency (44.62%). White-bellied Herons caught the majority (60.98%) of small sized fishes (≤ 9 cm) while facing upstream and the majority (60.92%) of large sized fishes (> 18 cm) while facing downstream. These findings shed light on the manner in which this rare and critically endangered bird is adapted to life on fast-flowing rivers and the importance of these unique places for its conservation.

The Gulf of Maine, USA is home to four colonial co-nesting tern species: Least Tern (Sternula antillarum), Common Tern (Sterna hirundo), Arctic Tern (Sterna paradisaea), and the federally endangered Roseate Tern (Sterna dougallii). Over three decades of visual observations of chick provisioning were compiled for a comparative dietary study in the region, including the first detailed descriptions of Least and Roseate Tern chick diets. Three prey groups comprised the majority of chick diets among tern species between 1986–2017: hake (Urophycis spp. or Enchelyopus cimbrius) 28–37% frequency of occurrence (FO), sand lance (Ammodytes americanus or A. dubius) 8–22% FO, and herring (Clupea spp. or Alosa spp.) 3–30% FO. Dietary contributions varied across species and islands. At two inshore colonies, Common Tern diets contained higher amounts of sand lance (30–42% FO), while offshore islands contained lesser amounts (5–9% FO). Overall dietary diversity (H′) was similar between Common (H′ = 1.57) and Arctic Terns (H′ = 1.74) and notably lower in Roseate (H′ = 1.24) and Least Terns (H′ = 1.37), whose diets were primarily piscivorous. The degree of dietary plasticity and general feeding ecology provided by baseline dietary information can inform holistic assessments of risk to ongoing and future disturbances from fishing and climate change.

Tropical farmlands experience dramatic seasonal variations in landscape conditions and have continuous human presence, providing potentially challenging settings for resident waterbirds. Behavior of the globally threatened Woolly-necked Stork (Ciconia episcopus) was studied for two seasons (monsoon and winter, 2018–2019) in lowland Nepal to assess how storks coped with changing conditions on farmlands. Activity budgets were prepared from 582 min of video, and recursive partitioning was used to identify variables that affected two critical activities: foraging and vigilance. Foraging was a dominant activity (32 ± 33%) with relatively little percent time spent being vigilant (10 ± 19%). Woolly-necked Storks reduced percent foraging time when they foraged closer (25.8 ± 36.3%) compared to farther (35.8 ± 31.8%) from wetlands. Percent foraging time was reduced during the winter (30.6 ± 35.2%) compared to monsoon (35.1 ± 32.2%), suggesting improved foraging conditions. Percent time spent foraging increased closer to humans, suggesting lower efficiency. Percent time being vigilant decreased closer to wetlands, suggesting reduced disturbance. Wetlands and drier cropfields with human presence were relatively high-value habitats. Woolly-necked Storks coped with changing seasonal conditions in lowland Nepal's farmlands by altering activity budgets in relatively minor ways identical to alterations made by similar species in wild habitats. This work adds to growing literature showcasing the multifunctional value of tropical agricultural landscapes and underscoring the need to move away from assuming that agriculture is uniformly detrimental for large waterbirds.

Four endemic species of wetland-dependent waterbirds occur on the main Hawaiian Islands, all of which have experienced sharp population declines and are listed as endangered species. Twice per year, state-wide surveys are conducted to count waterbirds, but these surveys are evaluated only infrequently. We used a state-space approach to evaluate long-term (1986–2016) and short-term (2006–2016) trends and current distribution and abundance of endemic Hawaiian waterbirds. The most numerous species was the Ae‘o, or Hawaiian Stilt (Himantopus mexicanus knudseni), with a 5-year estimated average abundance of 1,932 individuals, followed by ‘Alae Ke‘oke‘o, or Hawaiian Coot (Fulica alai), with 1,815 individuals, Alae ‘Ula, or Hawaiian Common Gallinule (Gallinula galeata sandvicensis) with 927 individuals, and the Koloa Maoli, or Hawaiian Duck (Anas wyvilliana) with 931 individuals. All four species had positive trends over the long-term, but short-term and island specific trends were more variable, and in some cases negative. These results provide valuable information to help guide management of Hawaii’s threatened and endangered endemic waterbirds.

Understanding the movements and habitat use of marine birds is essential to inform conservation and marine spatial planning. Here, satellite transmitters were used to study the migration and winter habitat use of adult Glaucous-winged Gulls (Larus glaucescens) from a colony in central British Columbia. Three of four tracked gulls overwintered locally, while the fourth followed a coastal migration route to northern California. All four gulls maintained small winter home ranges and spent an average of 72% of their time in nearshore coastal waters (average distance to coast: 0.6-1.7 km) characterized by low levels of anthropogenic activity. The remainder of their time was spent in naturally vegetated areas. One gull overwintered in an area with high human population density (northern California), with limited use of cropland (4% of locations) and urban (6% of locations) areas. This study is part of on-going efforts to understand the distribution and habitat use of marine birds throughout British Columbia to inform marine spatial planning and associated threats at various scales.

Florida's Big Bend region hosts the second largest concentration of breeding American Oystercatchers in the state, but reproductive success is low. Nest site characteristics and predation were examined to determine their influence on survival of nests and broods at two areas in the southern Big Bend (Cedar Key and Barge Canal). The probability of a nest surviving in Cedar Key was low (x̄ = 0.25, CI = 0.13–0.41) and limited by nest overwash (46% of known nest attempts); survival of nests at Barge Canal was much higher (x̄ = 0.45, CI = 0.31–0.58). However, 40% of chicks that survived to fledge (35 days) at Barge Canal died before reaching independence (60 days). Raccoon presence and hatch date were negatively correlated with brood survival at Barge Canal. Finally, chicks at Barge Canal weighed less and were smaller compared to chicks at an Atlantic Coast site, which may be related to low abundance of live oysters within 100 m of their nest sites. Efforts to enhance oystercatcher reproductive success may require different approaches for each site: habitat restoration to increase elevation of nest sites in Cedar Key and reduction of predators at Barge Canal.

Heterospecific disturbance in seabird colonies can negatively influence reproductive success both through direct effects, such as predation, and through indirect effects, such as increasing parental energy expenditure via defense behaviors. Here, remote nest cameras were used to evaluate the effects of intrusion on early nest survival and predation risk in Roseate Tern (Sterna dougallii) colonies in the U.S. and British Virgin Islands. Effects of colony traits such as colony size on parental nest defense were also investigated to assess individual response to predator presence in colonies. We counted 141 intrusion events at 118 nests and found that frequency of heterospecific disturbance did not influence nest survival, but did have a positive association with predation rate. Disturbance decreased significantly with colony size and % cover, and disturbance increased with nest density, indicating that concealed, isolated nests within large colonies were less likely to be disturbed. Parental nest defense decreased significantly with colony size and nest density. Results were likely driven by the dominant predator types in our system—large predatory birds and invasive rats—as parents were more likely to leave nests with intrusion from these predator types.

The nest site characteristics of two endangered seabird species–the Hawaiian Petrel Pterodroma sandwichensis and Newell's Shearwater Puffinus newelli–on Kaua‘i were considered. Burrows of both species were predominantly found under tree roots or small caves on steep slopes and were associated with native plants, both in the canopy (particularly Metrosideros polymorpha) and the understory (particularly Dicranopteris linearis). There were, however, marked differences between the two species. Hawaiian Petrels were found at higher elevations with a shorter, patchy canopy and more open understory. Models using microhabitat variables were better able to classify burrows than those using landscape topographic metrics, suggesting that metrics describing the immediate area around the burrow are more important to burrow selection. A comparative model indicated that elevation and maximum vegetation height were the strongest variables in classifying between the two species. Understanding microhabitat needs for these species is important for locating new colonies and for the successful implementation of management actions such as colony creation through social attraction. Furthermore, with the spread of Rapid’Ōhi’a Death canker disease Ceratocystis huliohia on Kaua‘i, the heavy reliance by both species on forest dominated by M. polymorpha (the tree killed by this disease) should be of increasing consideration for conservation efforts targeting these species.

Knowledge of the geographic linking of individuals or populations between different annual life cycle stages is essential for effective conservation decision making. The Willet (Tringa semipalmata) is composed of two distinct subspecies that are separated by breeding habitat in North America, with eastern Willets breeding in estuarine marshes along the Atlantic and Gulf Coasts and western Willets breeding in wet grasslands and prairies in the interior west of North America. We studied the migratory paths and wintering locations of Texas Gulf Coast breeding eastern Willets from 2015 to 2019 using light-level geolocators. Data analysis from 9 retrieved geolocators indicated that all birds departed Texas 5-26 July, made a 2–5-day flight, and arrived on the wintering grounds 8–30 July. All birds wintered on the Pacific coasts of Central and South America. In spring, the birds departed the wintering location 9–24 March, made a 3–4-day flight and arrived on the breeding grounds 12–27 March. These results are in contrast to previous work which showed that Atlantic breeding eastern Willets overwintered on the Atlantic coast in northern South America. This work has implications for shorebird conservation planning, which currently considers all Willets overwintering on the Pacific coast to be western Willets.

In wintering shorebird communities, interspecific niche segregation can occur by differences in diet, behavior, and morphology. The Lagoa do Peixe National Park (LPNP) is a coastal wetland complex with lagoons and sandy beaches in Southern Brazil, providing an environment with high prey availability where mixed-species foraging flocks of the Sanderling Calidris alba and the White-rumped Sandpiper Calidris fuscicollis occur. We counted all individuals in flocks and observed a higher proportion of Sanderlings than White-rumped Sandpipers foraging in the intertidal zone. To describe and evaluate patterns of trophic interactions between the two species, we built ethograms using video recordings and analyzed the foraging techniques and microhabitats used by individuals. The White-rumped Sandpiper (n = 45) was sighted foraging both in the supralittoral (n = 14) and intertidal zone (n = 31), whereas the Sanderling (n = 46) mostly foraged in the intertidal zone (n = 44). We estimated niche measures from foraging strategies and habitat preferences, which together can indicate dietary specialization. While niche width was similar for the two species, niche overlap was not significant, probably due to the different foraging microhabitats and techniques used by these two species. Therefore, the LPNP ecosystem offers diverse opportunities for wintering shorebirds, and is the southernmost area in which niche estimates of the Sanderling were assessed.

The overall population size and trend of the Magellanic Penguin (Spheniscus magellanicus) is uncertain and population estimates are available only for few locations. The last complete census along its central-southern distribution range in Argentina, province of Santa Cruz, was made in the 1990s. This study updates the breeding population size along Santa Cruz. Population estimates were compared with the last complete census, and trends were studied when it was possible. With 353,256 estimated breeding pairs, the overall population in Santa Cruz remained relatively stable after 25 years. The Santa Cruz population represents 31% of the Argentine Patagonian coast population and could represent between 22 and 30% of the species' global population. Colony sizes varied between 9 and 127,492 breeding pairs. Changes in abundance differed among locations, with individual colonies showing increasing, decreasing, or stable trends, which suggests that local factors determine population dynamics. The most significant increases (> 40%) were observed in the southern sector of Santa Cruz. Contrary to what was observed at the north of the distribution range in the province of Chubut, where trends of several colonies were inversely related to colony size, in Santa Cruz most of the largest colonies remained stable or even increased from the 1990s onwards.

The habitat of beach-nesting birds often overlaps with areas heavily used for human recreation. Human activity has been linked to negative behavioral and reproductive consequences for shorebirds; therefore, it is important for managers to understand how to best mitigate disturbance. In Florida, there is concern that human disturbance negatively affects the state-threatened population of Snowy Plovers (Charadrius nivosus). We measured response probabilities and flight initiation distances (FIDs) of Snowy Plovers at sites experiencing a range of human use. Snowy Plovers responded at longer distances to pedestrians and dogs than to competitor and predator species, except for incubating birds which responded at longer distances to predators. At all distances below 50 m, plovers had a response probability of > 0.2 for pedestrians. Dogs induced such strong reactions at close distances that plovers always displaced before they came within 20 m. Brood-rearing plovers were more sensitive to anthropogenic disturbance than plovers engaged in other behaviors. Plovers at sites with high disturbance generally had lower FIDs than birds at sites with less disturbance. Our findings illustrate the importance of accounting for differences in disturbance regimes among sites when setting buffer distances, and for protecting brood-rearing areas in addition to nesting habitat. Due to the severity of responses prompted by dogs, managers should strongly consider dog prohibitions at sites with breeding Snowy Plovers, as reasonable buffers may not be adequate.

Reinstating flood pulse dynamics has been identified as a method for restoring biotic communities in altered riverine ecosystems. To explore the impacts of flood pulse management on wet grassland bird communities, we surveyed community composition at a restored floodplain grassland in the Plain of Reeds region of the Mekong Delta. Survey sites were situated at different elevations, allowing us to sample the range of grassland habitats found in the study area. Our surveys coincided with three periods of decade-long water management; two surveys occurred during flood pulse water management, and another followed a decade of year-round high-water management. We used PERMANOVA and NMDS to compare avian community composition between these surveys and used foraging guilds to qualitatively assess the impact of water management separate from turnover in individual species. Community composition differed between all surveys at the lowest elevation site, with detection rates for species associated with ponded water, not grassland ecosystems, highest following high-water management. Some grassland species were absent following high-water management and may have been extirpated from survey sites. In the face of grassland loss across the Mekong Delta, our surveys highlight the value of continued flood pulse management for supporting the conservation of wet grassland birds.

Observations of individuals in unexpected places, often outside their known geographic range or in an unexpected part of their range seasonally, help better understand how individuals move across and use the landscape. Rallids (Family Rallidae) are a globally distributed family of birds which are well known for having vagrant individuals and to undertake mixed migration strategies. In this study, museum specimens and other records of Sora (Porzana carolina) outside of the western hemisphere are examined, along with individuals recovered outside of the breeding geographic range during Sora's typical breeding season (June–July). There were 5 museum specimens found outside the typical breeding range during the typical breeding season, 30 records from outside the typical breeding range during the typical breeding season, and 3 records outside of the Americas. Vagrancy and changes are possible pathways through which bird species may adapt to a changing climates and environments. Therefore, documentation and study of these vagrant movements is important to our overall understanding of rallid biology and will contribute to their conservation in the future.